Intravitreal injection as a minimally invasive procedure that has become an effective intervention in the management of numerous eye diseases. The procedure involves an active substance being directly injected into the vitreous cavity of the eye of a patient. Typically, the procedure is only used when the active substance does not easily penetrate into the eye, when applied by other means (such as topical or systemic), and where the active substance, or its vehicle, is not toxic to the intraocular tissue. The procedure bypasses anatomical barriers in the eye.
Intravitreal injection with administration of various agents has become a mainstay of treatment of conditions such as endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The most common example of when an intravitreal injection procedure is necessary is in the treatment of neovascular age-related macular degeneration with antivascular endothelial growth factor therapy. Antimicrobial intravitreal injections are also used to treat sight threatening intraocular infections such as endophthalmitis and cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome (AIDS).
The procedure of intravitreal injection is highly relevant in that macular degeneration is a leading cause of blindness in many societies. In developing regions of the world with limited financial resources for health care, the HIV/AIDS pandemic continues to unfold, and it may well be that cytomegalovirus retinitis will contribute significantly to world blindness. It is considered that at this time, the only viable treatment option in resource poor settings is injection of antiviral drugs via an intravitreal injection procedure.
Prior to injecting an active substance in to the intraocular tissue of the eye, the patient is given anaesthetic (topical and sometimes subconjunctival) to provide the required anaesthesia for sufficient patient comfort throughout the intravitreal injection procedure. A topical disinfectant, such as povidone iodine (and sometimes antibiotic), is then applied followed by the application of a mercury bag on top of the eye for 10 to 15 minutes to decompress and soften the globe which will reduce any intraocular pressure rise resulting from the subsequent injection.
A calliper set is then used to mark the injection site which is typically 3-4 mm from the limbus in the inferotemperal pars plana region of the eye. The syringe is then inserted at the injection site and aimed towards the mid-vitreous cavity after which the active is slowly injected. Topical antibiotics may be applied for 3 to 7 days post-injection.
In order to manage an intravitreal injection procedure, several instruments are needed all of which require sterilization prior to reuse. A speculum is needed to hold the eye open, a forcep is also used to hold and steady the eye during the injection as well as a set of callipers to measure the required distance from the limbus to the injection site. This level of instrumentation means that the person undertaking the intravitreal procedure must also have a significant degree of skill and experience with such medical procedures.
Accordingly, there is a need to provide a device for use during an intravitreal injection procedure, and/or a method of conducting an intravitreal injection procedure which reduces the number of instruments required during the procedure and/or reduces the complexity of the procedure.